County of Harris. §. By signing this contract, I choose to purchase the motor vehicle on credit according to the terms of this contract.A Texas Bill of Sale Vehicle Form is a formal document used to record the sale and transfer of ownership of a vehicle from one party to another. Learn about bill of sale laws and requirements for the state of Texas. Get templates for buying and selling high-value items like cars, boats, and firearms. The Texas bill of sale form verifies the elemental facts of the sale of personal property in exchange for a predetermined compensatory amount.